The tunnel was built because of concerns that crossing Skiff Street was too dangerous for users of the Farmington Canal Greenway. Construction money was found after the third phase of the project, which brought the trail to the New Haven line, had leftover funds.

"We were able to save over a million dollars of the budgeted cost. We asked the state Department of Transportation and the National Highway Administration for permission to use the unspent funds to build the long-sought underpass," Jackson told the audience Friday morning at the tunnel, below the rear entrance to the Super Stop & Shop at Dixwell Avenue.

Federal money paid for 80 percent of the $1 million and Hamden spent 20 percent.

Milone & MacBroom designed the tunnel and oversaw the work of Guerrera Construction of Oxford. The tunnel is 105 feet long, 14 feet wide and 10 feet high. It has two emergency call boxes, six lights, and five cameras that can be seen at police headquarters.

Some have said the town should not have spent $1 million on a tunnel.

But Jackson said the Farmington Canal trail is Hamden's best-used park. "We have an obligation to make it as safe as possible," Jackson said.

John Nutcher, a cyclist who uses it regularly, agreed.

"It's 5.5 miles from my house on Whitney Avenue to here. It was very dangerous crossing Skiff. Cars weren't accustomed to stopping for bikers and walkers," he said.

"Something was needed from the day we built the trail," said Vincent DeAngelis, an inspector who recently retired from Milone & MacBroom.